A hard disk apparatus, which is a type of magnetic recording and reproducing apparatus, includes a magnetic recording medium, and a magnetic head for recording data onto the medium and reproducing the data therefrom. Recently, recording density of the hard disk apparatus has been increased by 60% per year, and this trend is expected to continue in the future. Therefore, a magnetic recording head and a magnetic recording medium which are suitable for realization of high recording density have been developed.
A magnetic recording medium employed in a magnetic recording and reproducing apparatus or the like basically includes the structure as described below. On a substrate containing an Al alloy coated with Ni—P through plating or on a glass substrate, a non-magnetic undercoat layer for determining crystal orientation of a Co alloy layer is formed from Cr or a Cr alloy such as CrW or CrMo through sputtering among other methods. A thin film of Co alloy, serving as a magnetic layer, is formed on the non-magnetic undercoat layer. In addition, a protective film formed of an element such as carbon is provided on the magnetic layer, and if necessary, a lubricant such as perfluoropolyether is applied onto the protective film.
In recent years, requirement for high recording density of a magnetic recording medium has been increasing, and there has been demand for a magnetic recording medium which enables reduction in spacing loss (i.e., distance between a magnetic recording head and a magnetic layer). In order to reduce spacing loss, studies have been performed on thinning of a carbon protective film and reduction in the flying height of a magnetic recording head. In order to form a carbon protective film, sputtering or plasma CVD has been carried out.
A criterion for evaluating durability of a magnetic recording medium is fly stiction characteristic. The term “fly stiction characteristic” refers to a characteristic represented by a stiction value of a magnetic recording medium, which value is obtained when the medium is subjected to CSS (contact-start-stop) operation after the rotation of the medium and the flight of a magnetic head are maintained for a predetermined time. When the fly stiction characteristic of a magnetic recording medium is lowered, the flight stability of a magnetic head is lowered, which may result in problems such as head crush attributed to contact between a protective film and the magnetic head. Particularly, a medium of high recording density is used while the flying height of a magnetic head is maintained at a low level, and thus such a medium is demanded to exhibit excellent fly stiction characteristic.
However, a magnetic recording medium produced through the aforementioned conventional art may exhibit poor fly stiction characteristic. One of the reasons is thought to be as follows: when deposits are deposited onto the surface of such a magnetic recording medium in a magnetic recording and reproducing apparatus, and when the medium is employed for a prolonged period of time, the deposits are deposited onto a magnetic head, and thus fly stiction characteristic of the medium is lowered. One of such deposits is thought be a compound containing a gas component generated in the magnetic recording and reproducing apparatus or a compound which is formed through reaction between the gas component and an ionic substance contained in the apparatus, such as a metal. For example, a variety of members employed in the magnetic recording and reproducing apparatus are produced from plastic materials such as resin or photo-curing resins. A plasticizer such as a phthalate or a compound such as a photoreaction initiator is generated as an impurity gas component from such a material. Moreover, a lubricant employed in a pin of a connector part is present as an impurity gas component in the magnetic recording and reproducing apparatus. In order to maintain cleanliness of the magnetic recording and reproducing apparatus, the inside of the apparatus is segregated from the outside. Therefore, such a gas component generated inside the apparatus remains therein in a certain form, and a portion of the component is thought to become a deposit. When a magnetic head has the deposit on its surface, writing of data onto a magnetic recording medium or reading of the data therefrom may be unsatisfactory in practical use.
Therefore, there has been demand for a magnetic recording medium on which deposits are not easily deposited, the medium being employed in a magnetic recording and reproducing apparatus of high recording density. However, at the present time, there is no available method for inspecting the degree of difficulty in deposition of deposits onto a magnetic recording medium.